The technical scope of the present invention is that of laying systems for a weapon that ensure its stabilisation.
When a weapon is mounted on a mobile support, that is on a moving vehicle, its laying operations become very difficult to ensure since the weapon is subject to a certain number of disturbances. Firing from such a weapon requires it to be oriented in the direction of the target despite any movement be it linear or angular of the vehicle. One particularity of a vehicle able to move at high speeds (over 50 Km/H) cross country lies in the stresses to which it subjects the weapon and its laying system and which generally correspond to a high frequency level and cover a wide spectrum.
During travelling, these disturbances may come from:                the angular velocity of the support on which the weapon is mounted in traverse and that is located on the weapon at the motorization system,        the linear acceleration applied to the trunnions of the weapon via the off-centring of the centre of gravity,        the angular acceleration applied directly to the weapon by the friction appearing on the trunnions,        by the linear acceleration applied via the trunnions onto the weapon's centre of gravity causing its dynamic strain. In particular, when the frequency of the disturbance is close to the resonance frequency of the weapon itself, the weapon's own mode amplifies the natural strait to a ratio of several tens under the effect of the acceleration in question.        
Several methods and devices are known to mitigate the travel effects on the performance of a weapon.
A first method consists in measuring the disturbing angular velocity, for example using gyrometric style means and using it to control the rotational velocity of the motorization system placed between the support and the weapon. It is thus an anticipation control placed in parallel to an automatic control of the position of the weapon on an inertial reference whose efficiency is low so as to attenuate the amplitude of the angular disturbances at mean frequencies. Reference may be made, for example, to patent FR-80.21077.
Another method consists in providing motorization allowing the torque applied to the load to be controlled. This principle is used to improve the efficiency of the reduction in the effects of angular velocity disturbances. This method is suitable for low off-centring values. Reference may be made, for example, to patent U.S. Pat. No. 4,387,624.
When the off-centring between the axial position of the centre of gravity and the rotational axis increases, the performances obtained rapidly deteriorate through a combination of several mechanisms.
First of all, the off-centring of the centre of gravity increases the effect of the vertical acceleration produced (the unbalance effect) when travelling on the angular displacement of the weapon.
The increase in the motorization torque requirement caused by the dynamic torque requirement (in spite of the static equilibrating of the unbalance mass) leads in particular to the increase in inertia of the motor. The sensitivity of the system to mean frequency noises increases as a consequence, with as a corollary the necessity of increasing the filtering of all the sensors. The stabilisation performances are reduced along with the filtering of the sensors.
On certain weapon systems, functional constraints in particular related to the feeding principle of the weapon add to the off-centring of the centre of gravity of the geometric constraints that increase the friction at the trunnions with its effect on the orientation accuracy of the weapon.
Lastly, on other systems, to minimise the necessary volume at the rear and under the axis of orientation of the weapon, the assembly of this weapon requires the axis of orientation to be largely pushed back to the rear of the recoiling mass, this results in a substantial increase in the off-centring with its effect of the orientation accuracy, in particular during travel.